The present invention relates generally to a grain dryer, and more particularly to an apparatus and method for metering grain in a grain dryer.
In many instances, agricultural grain products must be stored for an extended period of time prior to being used. However, prior to storage, it is necessary to dry the grain to a condition in which it is less subject to molding or other deterioration. Accordingly, it has become known to remove moisture from grain by passing the grain through a grain dryer prior to storage.
Grain dryers typically have a plenum chamber through which heated air is advanced. The grain is passed through columns which surround the plenum chamber. Each column includes an inner perforated wall that is in fluid communication with the plenum chamber and an outer perforated wall which is in fluid communication with the ambient environment surrounding the grain dryer. As the grain moves through the column, heated air from the plenum chamber passes through the inner perforated wall, through the flow of grain, and out through the outer perforated wall. As the heated air moves through the flow of grain, moisture is removed from the grain.
To control the amount of moisture removed from the grain, it is necessary to precisely control the flow rate of the grain through the grain column. In particular, grain that remains in the grain column and is exposed to the heated air for an extended period of time may become too dry and even catch on fire, whereas grain that passes quickly through the grain column may retain an undesirable amount of moisture. To control the flow rate of grain through the grain column, a metering roll is utilized at a discharge opening of the grain column. In particular, the metering roll is located in a relatively narrow grain flow metering passage, and rotation of the metering roll within the metering passage causes grain to be advanced through the grain column at a desired rate. Controlling the speed of rotation of the metering roll controls the flow rate of grain through the grain dryer which, in turn, controls the amount of moisture removed from the grain.
A problem with grain dryers that have heretofore been designed is that an amount of residual grain cannot be removed from the metering passage of the grain dryer at or near the metering roll after a drying operation is completed. In particular, in the midst of a grain drying operation, grain advances out of the discharge opening of the grain column and through the metering passage until it reaches the metering roll. Thereafter, the metering roll advances dried grain from the metering passage to a transport bin. However, some of the dried grain may not be able to be advanced by the metering roll into the transport bin due to the geometry of the metering passage. As a result, a quantity of residual dried grain may be left in the metering passage. If this residual grain is not removed from the grain dryer within a reasonable amount of time, the residual grain may rot or sprout which is undesirable.
What is needed therefore is an apparatus and method for cleaning residual grain from a grain dryer which overcomes one or more of the abovementioned disadvantages.